Capnography

What is capnography?

Carbon dioxide (CO₂) is a gas produced by the body during metabolism and eliminated primarily through respiration. Monitoring its levels provides information about a patient's ventilation and can be especially useful in certain respiratory conditions and during sleep.

There are various methods for monitoring CO₂, including the measurement of CO₂ in exhaled air and transcutaneous CO₂ monitoring.

Measurement of CO₂ in exhaled air

Capnography allows for the monitoring of CO₂ present in the air a patient exhales. The device analyzes the exhaled gas and can display both the CO₂ value and its progression on a breath-by-breath basis through a graphical representation known as a capnogram.

This technique provides information primarily regarding ventilation and is used in various healthcare settings.

Normal values ​​in capnography

One of the parameters obtained is EtCO₂ (End-Tidal CO₂), which corresponds to the CO₂ measured at the end of exhalation.

In healthy adults, normal end-tidal carbon dioxide values ​​range between 35 and 45 mmHg.

These values ​​provide key information regarding:

• Adequate ventilation: values ​​within this range indicate that gas exchange in the lungs is efficient. 
• Hypoventilation: values ​​above 45 mmHg may indicate respiratory insufficiency or CO₂ retention. 
• Hyperventilation: values ​​below 35 mmHg may indicate excessive CO₂ elimination, often associated with stress, anxiety, or hypoxia.

Analyzing these figures helps healthcare professionals make quick and accurate decisions in various medical scenarios.

Transcutaneous CO₂ Monitoring

Another way to monitor CO₂ is through transcutaneous monitoring (PtcCO₂).

In this case, a sensor placed on the skin is used to continuously estimate CO₂ pressure.

Unlike capnography, which analyzes CO₂ in exhaled air, transcutaneous monitoring allows for continuous tracking of CO₂ levels without the need to directly collect exhaled air.

This feature makes it a particularly useful tool when prolonged monitoring is required, for example, for several hours or during sleep.

What is capnography used for?

Capnography provides information on CO₂ levels and can help identify ventilation abnormalities.

In the hospital setting, it can be used for:

1. Ventilation monitoring: allowing for the assessment of whether a patient is ventilating correctly and the early detection of respiratory problems.
2. Endotracheal tube placement confirmation: Based on the CO₂ values obtained, it ensures that the tube is correctly positioned during procedures such as intubation.
3. Monitoring in anesthesia: It assesses ventilatory status during surgery and ensures adequate CO₂ elimination.
4. Emergency monitoring: It facilitates the detection of hypoxia, hypercapnia, or hypocapnia in critical situations such as cardiac arrest.

In the home setting, it can be used, among other situations, to:

• Monitor ventilation during sleep.
• Detect possible increases in CO₂ associated with episodes of hypoventilation.
• Monitor patients using non-invasive home ventilation.
• Assess CO₂ levels over a prolonged period.
• Obtain additional information for monitoring and adjusting treatment, always within the framework of the assessment performed by the healthcare team.

The interpretation of CO₂ values should be performed in conjunction with the patient's other clinical and respiratory parameters.

Examples of capnography applications

1. Home setting: Monitoring of ventilation during sleep and of patients in their own homes. 
2. Intensive care: Monitoring of patients on mechanical ventilation to adjust ventilation parameters and prevent complications. 
3. Anesthesia: Monitoring during surgery to ensure adequate gas exchange and minimize risks. 
4. Medical emergencies: Rapid assessment of ventilation in critically ill patients, such as during cardiopulmonary resuscitation (CPR) or in cases of overdose. 
5. Prehospital medicine: A key tool in ambulances for determining the quality of ventilation and guiding initial care.

Transcutaneous monitoring during sleep

Changes in breathing and ventilation can occur during sleep. In certain patients, these changes may lead to an increase in CO₂ levels.

Transcutaneous monitoring allows for the recording of CO₂ levels over several hours, particularly during sleep.

The recording can provide information on:

• CO₂ trends throughout the night. 
• Potential episodes of hypoventilation. 
• Changes in ventilation during different stages of sleep. 
• The patient's response to ventilatory treatment.

Consequently, it can be a useful tool for the assessment and follow-up of certain patients with respiratory disorders or those using home-based ventilatory therapies.

Advantages of Transcutaneous Monitoring

Key features of capnography include:

• It does not require a blood draw for continuous CO₂ monitoring. 
• It allows for prolonged monitoring over several hours. 
• It can be used during sleep. 
• It enables recordings to be taken in the patient's home. 
• It provides complementary information for monitoring specific respiratory therapies. 
• Early detection of respiratory complications: it identifies issues such as airway obstructions, apnea, or hypoventilation before clear clinical signs appear. 
• Continuous monitoring: it provides constant, real-time information on the effectiveness of ventilation. 
• Risk reduction: it enhances patient safety by preventing complications related to anesthesia or mechanical ventilation. 
• Versatility: it is useful in various clinical settings, from operating rooms to emergency departments.

CO₂ Monitoring Equipment

At OXIGEN salud, we offer transcutaneous CO₂ monitoring equipment, as well as the accessories and consumables required for its use.

Our solutions enable continuous CO₂ monitoring in the home environment, facilitating the care of patients who require long-term assessment of their ventilation.

Contact us to find the solution best suited to your respiratory monitoring needs.